I shoot at 4 different clubs, when I can get to them, and every one welcomes any metalic sights, must depend on what part of the country you live in, I have a friend who lived his whole life in New York and has shot since the 60's and was able to shoot the peeps, he retired and moved to another state and there are no clubs that allow them,none. We have several guys who shoot opens right along beside the ams sights and still win their share of matches. I go to one club that allows any muzzleloader, any sight any projectile, yes they welcome all, they are trying to get more people involved knowing they will probably end up with a traditional rifle if they get hooked.
We do have primitive matches at these clubs that are separate from our line matches, these shoots are open sights only.
As for the NMLRA at Friendship there are matches for any muzzleloader, I think I am safe in saying if you have a muzzleloader you will have a match to shoot it in. You shoot aggs for the different types of sights and different types of ignition but you are not limited to just ams, opens, or scopes, if an agg says ams you can still use opens but no scope, if the match allows scopes you can still use opens or peeps, now if the agg calls for opens then opens is all you can use. If a guy wanted to he could take a flintlock with open sights and shoot in all of the matches, he would be competing against the percussion guns with peep sights if that's what the agg called for but he could still shoot in the agg. I hope I didn't confuse anyone.
There are hundreds of matches at Friendship, for every type of muzzleloader so you just have to pic the aggs/matches you want to shoot, I have always shot the offhand line matches, but there are trap, skeet, sporting clays,quailwalk for shotgun, pistol, bench/x-stick, primitive, silhouette, long range ml rifle, chunk, slug gun, woodswalk! I pretty much stay on the offhand line and take a truckload of guns along to shoot the various aggs. I do envy the fellow that grabs his rifle and pouch and goes to a match!! When I load up the truck for 9 days at Friendship I feel like I am moving!
Regards, Steve Chapman